1. Field of the Invention
This invention relates to a shielded safety syringe having an outer protective sleeve and a retractable needle which communicates with an evacuated blood collection tube at the interior of the sleeve. The needle may be relocated from an axially extended position relative to the outer sleeve, at which to draw a sample of blood through a targeted tissue area, to a retracted position, at which the needle is completely surrounded and shielded by the outer sleeve to avoid an accidental needle strike.
2. Prior Art.
Hypodermic syringes are used for a variety of purposes. By way of example, the syringe may be used for vacuum tube phlebotomy, where one or more samples of a patient's blood are successively drawn into respective evacuated blood collection tubes by way of a double ended hypodermic needle. Such a syringe may be used to treat a patient having a communicable disease. Prior to disposal of the syringe, the hypodermic needle is sometimes broken to prevent reuse. Health care workers are especially susceptible to accidental and potentially infectious needle strikes due to the careless handling or breaking of the needle and disposing of the syringe after use. The resulting mini-accidents caused by the accidental needle strike typically require a blood test for such diseases as AIDS and hepatitis. The corresponding cost and inefficiency of testing health care workers who have received an inadvertent needle strike result in considerable waste, which may be particularly damaging to a health care facility which is striving for economy.
The following U.S. patents provide examples of syringes having a hypodermic needle which may be shielded after use to prevent an accidental needle strike:
U.S. Pat. No. 2,571,653, Oct. 16, 1951 PA1 U.S. Pat. No. 4,356,822, Nov. 2, 1982 PA1 U.S. Pat. No. 4,425,120, Jan. 10, 1984 PA1 U.S. Pat. No. 4,631,057, Dec. 23, 1986
However, in the known shielded syringes, an outer sleeve is moved axially relative to a fixed hypodermic needle for either exposing or shielding the needle. Such shielded syringes are unlike the safety syringe which is disclosed below, where a hypodermic needle is moved axially relative to the fixed, outer protective sleeve, such that the needle may be relocated between axially extended and retracted positions.